/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/editors/screen/screen_draw.c
 *  \ingroup edscr
 */

#include "ED_screen.h"

#include "GPU_batch_presets.h"
#include "GPU_extensions.h"
#include "GPU_framebuffer.h"
#include "GPU_immediate.h"
#include "GPU_matrix.h"
#include "GPU_state.h"

#include "BLI_math.h"
#include "BLI_rect.h"

#include "WM_api.h"
#include "WM_types.h"

#include "UI_interface.h"
#include "UI_resources.h"

#include "screen_intern.h"

/**
 * Draw horizontal shape visualizing future joining (left as well right direction of future joining).
 */
static void draw_horizontal_join_shape(ScrArea *sa, char dir, unsigned int pos)
{
	const float width = screen_geom_area_width(sa) - 1;
	const float height = screen_geom_area_height(sa) - 1;
	vec2f points[10];
	short i;
	float w, h;

	if (height < width) {
		h = height / 8;
		w = height / 4;
	}
	else {
		h = width / 8;
		w = width / 4;
	}

	points[0].x = sa->v1->vec.x;
	points[0].y = sa->v1->vec.y + height / 2;

	points[1].x = sa->v1->vec.x;
	points[1].y = sa->v1->vec.y;

	points[2].x = sa->v4->vec.x - w;
	points[2].y = sa->v4->vec.y;

	points[3].x = sa->v4->vec.x - w;
	points[3].y = sa->v4->vec.y + height / 2 - 2 * h;

	points[4].x = sa->v4->vec.x - 2 * w;
	points[4].y = sa->v4->vec.y + height / 2;

	points[5].x = sa->v4->vec.x - w;
	points[5].y = sa->v4->vec.y + height / 2 + 2 * h;

	points[6].x = sa->v3->vec.x - w;
	points[6].y = sa->v3->vec.y;

	points[7].x = sa->v2->vec.x;
	points[7].y = sa->v2->vec.y;

	points[8].x = sa->v4->vec.x;
	points[8].y = sa->v4->vec.y + height / 2 - h;

	points[9].x = sa->v4->vec.x;
	points[9].y = sa->v4->vec.y + height / 2 + h;

	if (dir == 'l') {
		/* when direction is left, then we flip direction of arrow */
		float cx = sa->v1->vec.x + width;
		for (i = 0; i < 10; i++) {
			points[i].x -= cx;
			points[i].x = -points[i].x;
			points[i].x += sa->v1->vec.x;
		}
	}

	immBegin(GPU_PRIM_TRI_FAN, 5);

	for (i = 0; i < 5; i++) {
		immVertex2f(pos, points[i].x, points[i].y);
	}

	immEnd();

	immBegin(GPU_PRIM_TRI_FAN, 5);

	for (i = 4; i < 8; i++) {
		immVertex2f(pos, points[i].x, points[i].y);
	}

	immVertex2f(pos, points[0].x, points[0].y);
	immEnd();

	immRectf(pos, points[2].x, points[2].y, points[8].x, points[8].y);
	immRectf(pos, points[6].x, points[6].y, points[9].x, points[9].y);
}

/**
 * Draw vertical shape visualizing future joining (up/down direction).
 */
static void draw_vertical_join_shape(ScrArea *sa, char dir, unsigned int pos)
{
	const float width = screen_geom_area_width(sa) - 1;
	const float height = screen_geom_area_height(sa) - 1;
	vec2f points[10];
	short i;
	float w, h;

	if (height < width) {
		h = height / 4;
		w = height / 8;
	}
	else {
		h = width / 4;
		w = width / 8;
	}

	points[0].x = sa->v1->vec.x + width / 2;
	points[0].y = sa->v3->vec.y;

	points[1].x = sa->v2->vec.x;
	points[1].y = sa->v2->vec.y;

	points[2].x = sa->v1->vec.x;
	points[2].y = sa->v1->vec.y + h;

	points[3].x = sa->v1->vec.x + width / 2 - 2 * w;
	points[3].y = sa->v1->vec.y + h;

	points[4].x = sa->v1->vec.x + width / 2;
	points[4].y = sa->v1->vec.y + 2 * h;

	points[5].x = sa->v1->vec.x + width / 2 + 2 * w;
	points[5].y = sa->v1->vec.y + h;

	points[6].x = sa->v4->vec.x;
	points[6].y = sa->v4->vec.y + h;

	points[7].x = sa->v3->vec.x;
	points[7].y = sa->v3->vec.y;

	points[8].x = sa->v1->vec.x + width / 2 - w;
	points[8].y = sa->v1->vec.y;

	points[9].x = sa->v1->vec.x + width / 2 + w;
	points[9].y = sa->v1->vec.y;

	if (dir == 'u') {
		/* when direction is up, then we flip direction of arrow */
		float cy = sa->v1->vec.y + height;
		for (i = 0; i < 10; i++) {
			points[i].y -= cy;
			points[i].y = -points[i].y;
			points[i].y += sa->v1->vec.y;
		}
	}

	immBegin(GPU_PRIM_TRI_FAN, 5);

	for (i = 0; i < 5; i++) {
		immVertex2f(pos, points[i].x, points[i].y);
	}

	immEnd();

	immBegin(GPU_PRIM_TRI_FAN, 5);

	for (i = 4; i < 8; i++) {
		immVertex2f(pos, points[i].x, points[i].y);
	}

	immVertex2f(pos, points[0].x, points[0].y);
	immEnd();

	immRectf(pos, points[2].x, points[2].y, points[8].x, points[8].y);
	immRectf(pos, points[6].x, points[6].y, points[9].x, points[9].y);
}

/**
 * Draw join shape due to direction of joining.
 */
static void draw_join_shape(ScrArea *sa, char dir, unsigned int pos)
{
	if (dir == 'u' || dir == 'd') {
		draw_vertical_join_shape(sa, dir, pos);
	}
	else {
		draw_horizontal_join_shape(sa, dir, pos);
	}
}

#define CORNER_RESOLUTION 3

static void do_vert_pair(GPUVertBuf *vbo, uint pos, uint *vidx, int corner, int i)
{
	float inter[2], exter[2];
	inter[0] = cosf(corner * M_PI_2 + (i * M_PI_2 / (CORNER_RESOLUTION - 1.0f)));
	inter[1] = sinf(corner * M_PI_2 + (i * M_PI_2 / (CORNER_RESOLUTION - 1.0f)));

	/* Snap point to edge */
	float div = 1.0f / max_ff(fabsf(inter[0]), fabsf(inter[1]));
	mul_v2_v2fl(exter, inter, div);
	exter[0] = roundf(exter[0]);
	exter[1] = roundf(exter[1]);

	if (i == 0 || i == (CORNER_RESOLUTION - 1)) {
		copy_v2_v2(inter, exter);
	}

	/* Line width is 20% of the entire corner size. */
	const float line_width = 0.2f; /* Keep in sync with shader */
	mul_v2_fl(inter, 1.0f - line_width);
	mul_v2_fl(exter, 1.0f + line_width);

	switch (corner) {
		case 0:
			add_v2_v2(inter, (float[2]){-1.0f, -1.0f});
			add_v2_v2(exter, (float[2]){-1.0f, -1.0f});
			break;
		case 1:
			add_v2_v2(inter, (float[2]){1.0f, -1.0f});
			add_v2_v2(exter, (float[2]){1.0f, -1.0f});
			break;
		case 2:
			add_v2_v2(inter, (float[2]){1.0f, 1.0f});
			add_v2_v2(exter, (float[2]){1.0f, 1.0f});
			break;
		case 3:
			add_v2_v2(inter, (float[2]){-1.0f, 1.0f});
			add_v2_v2(exter, (float[2]){-1.0f, 1.0f});
			break;
	}

	GPU_vertbuf_attr_set(vbo, pos, (*vidx)++, inter);
	GPU_vertbuf_attr_set(vbo, pos, (*vidx)++, exter);
}

static GPUBatch *batch_screen_edges_get(int *corner_len)
{
	static GPUBatch *screen_edges_batch = NULL;

	if (screen_edges_batch == NULL) {
		GPUVertFormat format = {0};
		uint pos = GPU_vertformat_attr_add(&format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);

		GPUVertBuf *vbo = GPU_vertbuf_create_with_format(&format);
		GPU_vertbuf_data_alloc(vbo, CORNER_RESOLUTION * 2 * 4 + 2);

		uint vidx = 0;
		for (int corner = 0; corner < 4; ++corner) {
			for (int c = 0; c < CORNER_RESOLUTION; ++c) {
				do_vert_pair(vbo, pos, &vidx, corner, c);
			}
		}
		/* close the loop */
		do_vert_pair(vbo, pos, &vidx, 0, 0);

		screen_edges_batch = GPU_batch_create_ex(GPU_PRIM_TRI_STRIP, vbo, NULL, GPU_BATCH_OWNS_VBO);
		gpu_batch_presets_register(screen_edges_batch);
	}

	if (corner_len) {
		*corner_len = CORNER_RESOLUTION * 2;
	}
	return screen_edges_batch;
}

#undef CORNER_RESOLUTION

/**
 * Draw screen area darker with arrow (visualization of future joining).
 */
static void scrarea_draw_shape_dark(ScrArea *sa, char dir, unsigned int pos)
{
	GPU_blend_set_func_separate(GPU_SRC_ALPHA, GPU_ONE_MINUS_SRC_ALPHA, GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);
	immUniformColor4ub(0, 0, 0, 50);

	draw_join_shape(sa, dir, pos);
}

/**
 * Draw screen area lighter with arrow shape ("eraser" of previous dark shape).
 */
static void scrarea_draw_shape_light(ScrArea *sa, char UNUSED(dir), unsigned int pos)
{
	GPU_blend_set_func(GPU_DST_COLOR, GPU_SRC_ALPHA);
	/* value 181 was hardly computed: 181~105 */
	immUniformColor4ub(255, 255, 255, 50);
	/* draw_join_shape(sa, dir); */

	immRectf(pos, sa->v1->vec.x, sa->v1->vec.y, sa->v3->vec.x, sa->v3->vec.y);
}

static void drawscredge_area_draw(int sizex, int sizey, short x1, short y1, short x2, short y2, float edge_thickness)
{
	rctf rect;
	BLI_rctf_init(&rect, (float)x1, (float)x2, (float)y1, (float)y2);

	/* right border area */
	if (x2 >= sizex - 1) {
		rect.xmax += edge_thickness * 0.5f;
	}

	/* left border area */
	if (x1 <= 0) { /* otherwise it draws the emboss of window over */
		rect.xmin -= edge_thickness * 0.5f;
	}

	/* top border area */
	if (y2 >= sizey - 1) {
		rect.ymax += edge_thickness * 0.5f;
	}

	/* bottom border area */
	if (y1 <= 0) {
		rect.ymin -= edge_thickness * 0.5f;
	}

	GPUBatch *batch = batch_screen_edges_get(NULL);
	GPU_batch_uniform_4fv(batch, "rect", (float *)&rect);
	GPU_batch_draw(batch);
}

/**
 * \brief Screen edges drawing.
 */
static void drawscredge_area(ScrArea *sa, int sizex, int sizey, float edge_thickness)
{
	short x1 = sa->v1->vec.x;
	short y1 = sa->v1->vec.y;
	short x2 = sa->v3->vec.x;
	short y2 = sa->v3->vec.y;

	drawscredge_area_draw(sizex, sizey, x1, y1, x2, y2, edge_thickness);
}

/**
 * Only for edge lines between areas.
 */
void ED_screen_draw_edges(wmWindow *win)
{
	bScreen *screen = WM_window_get_active_screen(win);
	screen->do_draw = false;

	if (screen->state == SCREENFULL) {
		return;
	}

	const int winsize_x = WM_window_pixels_x(win);
	const int winsize_y = WM_window_pixels_y(win);
	float col[4], corner_scale, edge_thickness;
	int verts_per_corner = 0;

	ScrArea *sa;

	rcti scissor_rect;
	BLI_rcti_init_minmax(&scissor_rect);
	for (sa = screen->areabase.first; sa; sa = sa->next) {
		BLI_rcti_do_minmax_v(&scissor_rect, (int[2]){sa->v1->vec.x, sa->v1->vec.y});
		BLI_rcti_do_minmax_v(&scissor_rect, (int[2]){sa->v3->vec.x, sa->v3->vec.y});
	}

	if (GPU_type_matches(GPU_DEVICE_INTEL_UHD, GPU_OS_UNIX, GPU_DRIVER_ANY)) {
		/* For some reason, on linux + Intel UHD Graphics 620 the driver
		 * hangs if we don't flush before this. (See T57455) */
		GPU_flush();
	}

	GPU_scissor(scissor_rect.xmin,
	            scissor_rect.ymin,
	            BLI_rcti_size_x(&scissor_rect) + 1,
	            BLI_rcti_size_y(&scissor_rect) + 1);

	/* It seems that all areas gets smaller when pixelsize is > 1.
	 * So in order to avoid missing pixels we just disable de scissors. */
	if (U.pixelsize <= 1.0f) {
		glEnable(GL_SCISSOR_TEST);
	}

	UI_GetThemeColor4fv(TH_EDITOR_OUTLINE, col);
	col[3] = 1.0f;
	corner_scale = U.pixelsize * 8.0f;
	edge_thickness = corner_scale * 0.21f;

	GPU_blend(true);

	GPUBatch *batch = batch_screen_edges_get(&verts_per_corner);
	GPU_batch_program_set_builtin(batch, GPU_SHADER_2D_AREA_EDGES);
	GPU_batch_uniform_1i(batch, "cornerLen", verts_per_corner);
	GPU_batch_uniform_1f(batch, "scale", corner_scale);
	GPU_batch_uniform_4fv(batch, "color", col);

	for (sa = screen->areabase.first; sa; sa = sa->next) {
		drawscredge_area(sa, winsize_x, winsize_y, edge_thickness);
	}

	GPU_blend(false);

	if (U.pixelsize <= 1.0f) {
		glDisable(GL_SCISSOR_TEST);
	}
}

/**
 * The blended join arrows.
 *
 * \param sa1: Area from which the resultant originates.
 * \param sa2: Target area that will be replaced.
 */
void ED_screen_draw_join_shape(ScrArea *sa1, ScrArea *sa2)
{
	uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
	immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);

	GPU_line_width(1);

	/* blended join arrow */
	int dir = area_getorientation(sa1, sa2);
	int dira = -1;
	if (dir != -1) {
		switch (dir) {
			case 0: /* W */
				dir = 'r';
				dira = 'l';
				break;
			case 1: /* N */
				dir = 'd';
				dira = 'u';
				break;
			case 2: /* E */
				dir = 'l';
				dira = 'r';
				break;
			case 3: /* S */
				dir = 'u';
				dira = 'd';
				break;
		}

		GPU_blend(true);

		scrarea_draw_shape_dark(sa2, dir, pos);
		scrarea_draw_shape_light(sa1, dira, pos);

		GPU_blend(false);
	}

	immUnbindProgram();
}

void ED_screen_draw_split_preview(ScrArea *sa, const int dir, const float fac)
{
	uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
	immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);

	/* splitpoint */
	GPU_blend(true);
	immUniformColor4ub(255, 255, 255, 100);

	immBegin(GPU_PRIM_LINES, 2);

	if (dir == 'h') {
		const float y = (1 - fac) * sa->totrct.ymin + fac * sa->totrct.ymax;

		immVertex2f(pos, sa->totrct.xmin, y);
		immVertex2f(pos, sa->totrct.xmax, y);

		immEnd();

		immUniformColor4ub(0, 0, 0, 100);

		immBegin(GPU_PRIM_LINES, 2);

		immVertex2f(pos, sa->totrct.xmin, y + 1);
		immVertex2f(pos, sa->totrct.xmax, y + 1);

		immEnd();
	}
	else {
		BLI_assert(dir == 'v');
		const float x = (1 - fac) * sa->totrct.xmin + fac * sa->totrct.xmax;

		immVertex2f(pos, x, sa->totrct.ymin);
		immVertex2f(pos, x, sa->totrct.ymax);

		immEnd();

		immUniformColor4ub(0, 0, 0, 100);

		immBegin(GPU_PRIM_LINES, 2);

		immVertex2f(pos, x + 1, sa->totrct.ymin);
		immVertex2f(pos, x + 1, sa->totrct.ymax);

		immEnd();
	}

	GPU_blend(false);

	immUnbindProgram();
}


/* -------------------------------------------------------------------- */
/* Screen Thumbnail Preview */

/**
 * Calculates a scale factor to squash the preview for \a screen into a rectangle of given size and aspect.
 */
static void screen_preview_scale_get(
        const bScreen *screen, float size_x, float size_y,
        const float asp[2],
        float r_scale[2])
{
	float max_x = 0, max_y = 0;

	for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
		max_x = MAX2(max_x, sa->totrct.xmax);
		max_y = MAX2(max_y, sa->totrct.ymax);
	}
	r_scale[0] = (size_x * asp[0]) / max_x;
	r_scale[1] = (size_y * asp[1]) / max_y;
}

static void screen_preview_draw_areas(const bScreen *screen, const float scale[2], const float col[4],
                                      const float ofs_between_areas)
{
	const float ofs_h = ofs_between_areas * 0.5f;
	uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);

	immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
	immUniformColor4fv(col);

	for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
		rctf rect = {
			.xmin = sa->totrct.xmin * scale[0] + ofs_h,
			.xmax = sa->totrct.xmax * scale[0] - ofs_h,
			.ymin = sa->totrct.ymin * scale[1] + ofs_h,
			.ymax = sa->totrct.ymax * scale[1] - ofs_h
		};

		immBegin(GPU_PRIM_TRI_FAN, 4);
		immVertex2f(pos, rect.xmin, rect.ymin);
		immVertex2f(pos, rect.xmax, rect.ymin);
		immVertex2f(pos, rect.xmax, rect.ymax);
		immVertex2f(pos, rect.xmin, rect.ymax);
		immEnd();
	}

	immUnbindProgram();
}

static void screen_preview_draw(const bScreen *screen, int size_x, int size_y)
{
	const float asp[2] = {1.0f, 0.8f}; /* square previews look a bit ugly */
	/* could use theme color (tui.wcol_menu_item.text), but then we'd need to regenerate all previews when changing */
	const float col[4] = {1.0f, 1.0f, 1.0f, 1.0f};
	float scale[2];

	wmOrtho2(0.0f, size_x, 0.0f, size_y);
	/* center */
	GPU_matrix_push();
	GPU_matrix_identity_set();
	GPU_matrix_translate_2f(size_x * (1.0f - asp[0]) * 0.5f, size_y * (1.0f - asp[1]) * 0.5f);

	screen_preview_scale_get(screen, size_x, size_y, asp, scale);
	screen_preview_draw_areas(screen, scale, col, 1.5f);

	GPU_matrix_pop();
}

/**
 * Render the preview for a screen layout in \a screen.
 */
void ED_screen_preview_render(const bScreen *screen, int size_x, int size_y, unsigned int *r_rect)
{
	char err_out[256] = "unknown";
	GPUOffScreen *offscreen = GPU_offscreen_create(size_x, size_y, 0, true, false, err_out);

	GPU_offscreen_bind(offscreen, true);
	GPU_clear_color(0.0, 0.0, 0.0, 0.0);
	GPU_clear(GPU_COLOR_BIT | GPU_DEPTH_BIT);

	screen_preview_draw(screen, size_x, size_y);

	GPU_offscreen_read_pixels(offscreen, GL_UNSIGNED_BYTE, r_rect);
	GPU_offscreen_unbind(offscreen, true);

	GPU_offscreen_free(offscreen);
}
